Two-stage method for treating calcified lesions within the wall of a blood vessel

Abstract

A method is disclosed for treating calcified lesions within a wall of a blood vessel. The first step includes breaking apart a calcified lesion using a plurality of shockwaves generated in an angioplasty balloon of an angioplasty catheter device. The angioplasty balloon is dilated via a fluid to a first extent to fit against at least a portion of the wall of the blood vessel. A plurality of electrical pulses are delivered to a pair of electrodes disposed within the fluid inside the balloon. The electrical pulses have an amplitude sufficient to create plasma arcs in the fluid to generate shockwaves that are conducted through the fluid and through the balloon to the blood vessel, to crack the calcified lesion. After breaking apart the calcified lesion, the angioplasty balloon is allowed to further expand to a second extent greater than the first extent, thereby expanding an opening in the blood vessel.

The invention claimed is: 
     
       1. A method for treating calcified lesions within a wall of a blood vessel in a patient, the method comprising:
 i) breaking apart a calcified lesion within the wall of the blood vessel using a plurality of shockwaves generated in an angioplasty balloon of an angioplasty catheter device, wherein
 the angioplasty catheter device includes a guidewire sheath and is disposed on a guidewire while the angioplasty balloon is dilated via a fluid to a first extent to fit against at least a portion of the wall of the blood vessel, and 
 breaking apart the calcified lesion comprises delivering, via a pulse generator, a plurality of electrical pulses to an electrode pair disposed within the angioplasty balloon and exposed to the fluid, each pulse having an amplitude sufficient to create a plasma in the fluid, wherein
 the plurality of pulses create a plurality of plasma arcs at the electrode pair such that the plurality of shockwaves is conducted through the fluid and through the angioplasty balloon to the blood vessel, thereby delivering mechanical energy to the calcified lesion to crack the calcified lesion; and 
 
 
 ii) allowing the angioplasty balloon to further expand to a second extent greater than the first extent in response to the breaking apart of the calcified lesion, thereby expanding an opening in the blood vessel. 
 
     
     
       2. The method of  claim 1 , wherein delivering the plurality of pulses comprises varying, between a series of two pulses of the plurality of pulses, at least one of a pulse duration or a voltage magnitude to alter a shockwave intensity. 
     
     
       3. The method of  claim 1 , wherein delivering the plurality of pulses comprises varying, during delivery, a repetition rate of the plurality of pulses. 
     
     
       4. The method of  claim 1 , wherein the amplitude of each pulse of the plurality of pulses is within a range of 1000 to 3000 volts. 
     
     
       5. The method of  claim 1 , wherein the plurality of shockwaves each travel radially through the fluid and through the angioplasty balloon, the plurality of shockwaves delivering energy through an extent of the angioplasty balloon from a proximal end of the angioplasty balloon to a distal end of the angioplasty balloon. 
     
     
       6. The method of  claim 1 , wherein allowing the angioplasty balloon to further expand comprises smoothing an intima of the blood vessel. 
     
     
       7. The method of  claim 1 , wherein allowing the angioplasty balloon to further expand comprises smoothing and restoring an intima of the blood vessel. 
     
     
       8. The method of  claim 1 , wherein cracking the calcified lesion comprises focusing the plurality of shockwaves. 
     
     
       9. The method of  claim 1 , wherein cracking the calcified lesion comprises detecting a cardiac R wave of a heart of the patient and wherein creating the plurality of plasma arcs comprises synchronizing each arc of the plurality of plasma arcs with the cardiac R wave. 
     
     
       10. The method of  claim 1 , wherein cracking the calcified lesion comprises pulverizing at least a portion of the calcified lesion. 
     
     
       11. The method of  claim 1 , wherein the electrode pair is disposed radially external to the guidewire sheath. 
     
     
       12. The method of  claim 1 , wherein the distal end of the guidewire sheath extends beyond the distal end of the balloon. 
     
     
       13. The method of  claim 1  wherein when the angioplasty balloon is dilated to the first extent, the angioplasty balloon fits snugly against the wall of the blood vessel. 
     
     
       14. The method of  claim 1  wherein the fluid is a conductive liquid. 
     
     
       15. A method of treating calcified lesions within the wall of a blood vessel comprising:
 inserting a guide wire into the blood vessel; 
 advancing an angioplasty catheter into the blood vessel over the guide wire, said angioplasty catheter having a guidewire sheath, a fluid-fillable angioplasty balloon, and a shockwave generator located within the angioplasty balloon, wherein the shockwave generator is defined by a pair of spaced apart electrodes disposed inside the angioplasty balloon and exposed to the fluid; 
 expanding the angioplasty balloon with the fluid so that the angioplasty balloon presses against at least a portion of a calcified wall of the blood vessel; 
 after the expanding, supplying one or more electrical pulses to the shockwave generator, each pulse sufficient to create a plasma arc between the pair of spaced apart electrodes resulting in a mechanical shock wave within the angioplasty balloon that passes through the fluid, through the angioplasty balloon, and into the calcified wall of the blood vessel to crack calcified lesions within the calcified wall of the blood vessel; and 
 after the supplying, allowing the angioplasty balloon to further expand in response to the cracking of the calcified lesions thereby expanding an opening in the blood vessel. 
 
     
     
       16. The method of  claim 15 , further comprising detecting cardiac R waves of the patient's heart, wherein
 supplying the one or more electrical pulses comprises timing the one or more electrical pulses to synchronize the mechanical shock waves with the detected R waves. 
 
     
     
       17. The method of  claim 15 , wherein the angioplasty balloon is radially symmetric about a longitudinal axis of the angioplasty catheter, wherein
 the guide wire sheath surrounds the longitudinal axis. 
 
     
     
       18. The method of  claim 15 , wherein the electrode pair are disposed radially external to the guidewire sheath. 
     
     
       19. The method of  claim 15 , wherein the distal end of the guidewire sheath extends beyond the distal end of the balloon. 
     
     
       20. The method of  claim 15 , wherein when the angioplasty balloon is initially expanded, the angioplasty balloon fits snugly against the wall of the blood vessel. 
     
     
       21. The method of  claim 15  wherein the fluid is a conductive liquid.